Synthesis of ortho-palladated phenol derivatives. Study of their reactivity with carbon monoxide and isonitriles

Article abstract of DOI:10.1021/om010074z

The reaction of 2-ROC₆H₄I with [Pd₂(dba)₃]·dba ("Pd(dba)₂" dba = dibenzylideneacetone) in the presence of the appropriate ligand results in the formation of the arylpalladium complexes trans-[Pd(C₆H₄OR-2)I(PPh₃)₂] (R = H (1a), C(O)Me (1b), C(O)CH=CH₂ (1c)) and [Pd(C₆H₄OR-2)I(bpy)] (bpy = 2,2′-bipyridine; R = H (2a), C(O)Me (2b)). Complexes 1b and 1c react with bpy in the presence of Tl(OTf) (OTf = OSO₂CF₃) to give the cationic species [Pd(C₆H₄OR-2)(bpy)(PPh₃)]OTf (R = C(O)Me (3b), C(O)CH=CH₂ (3c)). Complex 1a reacts with carbon monoxide, yielding the insertion complex trans-[Pd{C(O)C₆H₄OH-2}I(PPh₃)₂] (4a). Complexes 2a and 2b can also be carbonylated to give [Pd{C(O)C₆H₄OR-2}I(bpy)] (R = H (5a), C(O)Me (5b)). Complex 4a reacts with bpy and Tl(OTf), giving [Pd{C(O)C₆H₄OH-2}(bpy)(PPh₃)]OTf (6a). The reaction of 2-ROC₆H₄I with Pd(dba)₂ and isonitriles R′NC gives rise to the complexes trans-[Pd{C(=NR′)C₆H₄OR-2}I(CNR′)₂] (R = H, R′ = Xy = 2,6-dimethylphenyl) (7a), R′ = ^tBu (7a*); R = C(O)Me, R′ = Xy (7b), R′ = ^tBu (7b*). Complexes 7a and 7b* can also be prepared by ligand displacement from 2a and 2b and XyNC and ^tBuNC, respectively. Complexes 2a and 2b react with R′NC (1:1) to give [Pd{C(=NR′)C₆H₄OR-2}I(bpy)] (R = H, R′ = Xy (8a), R′ = ^tBu (8a*);R = C(O)Me, R′ = Xy (8b)). Complex 7a reacts with bpy in the presence of Tl(OTf), yielding [Pd{C(=NR′)C₆H₄OH-2}(CNR′)(bpy)]-OTf (9a). Reaction of 5a with R′NC gives trans-[Pd{C(O)C₆H₄OH-2}I(CNR′)₂] (R′ = Xy (10a), ^tBu (10a*)), which, in turn, react with further R′NC in the presence of Tl(OTf) to give [Pd{C(O)C₆H₄OH-2}(CNR′)₃]OTf (R′ = Xy (11a), ^tBu (11a*)). Finally, the reaction of 7 with Pd(OAc)₂ results in the tetrameric [Pd{Κ²(C,O)-μ₂(O)-C(=NXy)C₆ H₄O-2}(CNXy)]₄ (12) and trans-[PdI₂ (CNXy)₂]. Most of the reported aroyl (4-6, 10, 11) and iminoaroyl (7-9, 12) derivatives are new types of palladium complexes. The crystal structures of complexes 5a, 7a, 7b, 8b, 9a, and 12 have been determined by X-ray diffraction methods. The following scale of trans influence has been established: bpy < I < C(=NXy)C₆H₄OC(O)Me-2 ≈ C(=O)C₆H₄OH-2 < C(=NXy)C₆H₄OH-2.

Full text of DOI:10.1021/om010074z

2704
Organometallics 2001, 20, 2704-2715
Syn th esis of Or th o-P a lla d a ted P h en ol Der iva tives. Stu d y
of Th eir Rea ctivity w ith Ca r bon Mon oxid e a n d
Ison itr iles
J ose´ Vicente,*,† J ose´-Antonio Abad,*,‡ and Walter Fo¨rtsch
Grupo de Quı´mica Organometa´lica, Departamento de Quı´mica Inorga´nica,
Facultad de Quı´mica, Universidad de Murcia, Aptdo. 4021, E-30071 Murcia, Spain
Peter G. J ones*,§
Institut fu¨r Anorganische und Analytische Chemie, Technische Universita¨t Braunschweig,
Postfach 3329, 38023 Braunschweig, Germany
Axel K. Fischer
Institut fu¨r Chemie, Universita¨t Magdeburg, Universita¨tsplatz 2, 37106 Magdeburg, Germany
Received J anuary 30, 2001
The reaction of 2-ROC6H4I with [Pd2(dba)3]‚dba (“Pd(dba)2”; dba ) dibenzylideneacetone)
in the presence of the appropriate ligand results in the formation of the arylpalladium
complexes trans-[Pd(C6H4OR-2)I(PPh3)2] (R ) H (1a ), C(O)Me (1b), C(O)CHdCH2 (1c)) and
[Pd(C6H4OR-2)I(bpy)] (bpy ) 2,2′-bipyridine; R ) H (2a ), C(O)Me (2b)). Complexes 1b and
1c react with bpy in the presence of Tl(OTf) (OTf ) OSO2CF3) to give the cationic species
[Pd(C6H4OR-2)(bpy)(PPh3)]OTf (R ) C(O)Me (3b), C(O)CHdCH2 (3c)). Complex 1a reacts
with carbon monoxide, yielding the insertion complex trans-[Pd{C(O)C6H4OH-2}I(PPh3)2]
(4a ). Complexes 2a and 2b can also be carbonylated to give [Pd{C(O)C6H4OR-2}I(bpy)] (R
) H (5a ), C(O)Me (5b)). Complex 4a reacts with bpy and Tl(OTf), giving [Pd{C(O)C6H4OH-
2}(bpy)(PPh3)]OTf (6a ). The reaction of 2-ROC6H4I with Pd(dba)2 and isonitriles R′NC gives
rise to the complexes trans-[Pd{C(dNR′)C6H4OR-2}I(CNR′)2] (R ) H, R′ ) Xy ) 2,6-
dimethylphenyl) (7a ), R′ ) tBu (7a *); R ) C(O)Me, R′ ) Xy (7b), R′ ) tBu (7b*)). Complexes
7a and 7b* can also be prepared by ligand displacement from 2a and 2b and XyNC and
tBuNC, respectively. Complexes 2a and 2b react with R′NC (1:1) to give [Pd{C(dNR′)C6H4-
OR-2}I(bpy)] (R ) H, R′ ) Xy (8a ), R′ ) tBu (8a *); R ) C(O)Me, R′ ) Xy (8b)). Complex 7a
reacts with bpy in the presence of Tl(OTf), yielding [Pd{C(dNR′)C6H4OH-2}(CNR′)(bpy)]-
OTf (9a ). Reaction of 5a with R′NC gives trans-[Pd{C(O)C6H4OH-2}I(CNR′)2] (R′ ) Xy (10a ),
tBu (10a *)), which, in turn, react with further R′NC in the presence of Tl(OTf) to give [Pd-
t
{C(O)C6H4OH-2}(CNR′)3]OTf (R′ ) Xy (11a ), Bu (11a *)). Finally, the reaction of 7a with
Pd(OAc)2 results in the tetrameric [Pd{κ2(C,O)-µ2(O)-C(dNXy)C6H4O-2}(CNXy)]4 (12) and
trans-[PdI2(CNXy)2]. Most of the reported aroyl (4-6, 10, 11) and iminoaroyl (7-9, 12)
derivatives are new types of palladium complexes. The crystal structures of complexes 5a ,
7a , 7b, 8b, 9a , and 12 have been determined by X-ray diffraction methods. The following
scale of trans influence has been established: bpy < I < C(dNXy)C6H4OC(O)Me-2 ≈
C(dO)C6H4OH-2 < C(dNXy)C6H4OH-2.
In tr od u ction
synthesis of complexes with X ) OH, OC(O)Me, and
OC(O)CHdCH2. These complexes seem to play an
important role in some palladium-catalyzed processes,
We have shown that (2-X-aryl)palladium complexes
have interesting properties when X is a reactive sub-
stituent such as CHO, C(O)Me, C(O)NHR, NH2, NO2,
CN, and CHdCH2.1-11 In this paper we report the
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† E-mail: jvs@um.es; http://www.scc.um.es/gi/gqo/.
‡ E-mail: jaab@um.es.
§ E-mail: jones@xray36.anchem.nat.tu-bs.de.
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10.1021/om010074z CCC: $20.00 © 2001 American Chemical Society
Publication on Web 05/26/2001

Ortho-Palladated Phenol Derivatives
Organometallics, Vol. 20, No. 13, 2001 2705
e.g., in the formation of o-alkynylphenols, which are
intermediates in the formation of benzofurans.12-14
Similarly, ortho-palladated O-substituted phenol de-
rivatives may be catalytic intermediates in intramo-
lecular cyclizations to give 4-methylcoumarin,15,16 1,3-
benzoxazepin-2-ones,17 or benzopyrans.18 However, as
far as we are aware, ortho-palladated phenol or phenol
ester derivatives have not yet been isolated; in this
work, we report on the synthesis of these types of
complexes and on their reactivity with carbon monoxide
and isonitriles.
The insertion of CO into the Pd-C bond, resulting in
the formation of acylpalladium derivatives, constitutes
a key step in the palladium-catalyzed carbonylation of
organic substrates in laboratory synthesis and also in
industrial processes.19-24 These CO insertions are also
relevant in the palladium-catalyzed copolymerization of
CO and unsaturated organic substrates.25-39 This is
the reason for the extensive study of insertion reac-
tions.21,40-44 However, most studies of insertion reac-
tions of CO into Pd-C bonds have been devoted to alkyl,
mainly methyl, derivatives.24,40,43-50 Only mononuclear
phenyl- or alkyl-substituted phenyl46,51-56 and dinuclear
1,4-phenylene and 4,4′-biphenyl57 palladium complexes
have been carbonylated. The rates of reaction of a
variety of trans-[Pd(Ar)X(PPh3)2] (Ar ) C6H4R-4, R )
H, NO2, Me, CN, CF3, OMe; X ) Cl, Br, I) complexes
with CO have been studied, but the resulting complexes
have not been isolated.58 We have isolated the first
carbonylation products of functionalized arylpalladium-
(II) complexes, [Pd(C6H4NH2-2)I(bpy)] and [Pd(C6H4-
NH2-2)I(PR3)] (R ) Ph, C6H4Me-4).2,5 Norbornene,59,60
norbornadiene,61 allenes,62 or internal alkynes63 react
with o-iodophenol in the presence of carbon monoxide
and a palladium catalyst to afford coumaranone,
chromone, or coumarin derivatives. In this paper, we
report the carbonylation reactions of some ortho-palla-
dated complexes of phenol and some of its derivatives
that could be intermediates in some of these catalytic
systems.
Insertion reactions of isonitriles into Pd-C bonds also
constitute a subject of great interest,4,44,45,57,64-69 since
they can lead to new types of organopalladium4,44,45,57,64-79
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2706 Organometallics, Vol. 20, No. 13, 2001
Vicente et al.
1
Yield: 120 mg, 21%. Mp: 161 °C. H NMR (300 MHz, CDCl3;
complexes and because they may be important for
organic synthesis.4,69,79-85
ppm): 7.78-7.48 (m, PPh3, 12H), 7.39-7.22 (m, PPh3, 18H),
6.57 (d, C6H4, 1H, J HH ) 7.8 Hz), 6.38 (dd, C6H4, 1H, J HH
3
3
)
3
3
7.5 Hz, J HH ) 7.8 Hz), 6.03 (dd, C6H4, 1H, J HH ) 7.5 Hz,
3J HH ) 7.2 Hz), 5.78 (d, C6H4, 1H, 3J HH ) 7.2 Hz), 4.99 (s, OH,
1H). 13C{1H} NMR (50 MHz, CDCl3; ppm): 155.05 (t, COH,
Exp er im en ta l Section
Reactions were carried out without precautions to exclude
atmospheric moisture, unless otherwise stated. The IR and
C, H, and N analyses and melting point determinations were
carried out as described elsewhere.10 Unless otherwise stated,
NMR spectra were recorded in CDCl3 in a Varian Unity 300
or a Bruker Unity 200. Chemical shifts were referenced to TMS
(1H and 13C(1H)) and PO4H3 (31P). Chromatographic separa-
tions were carried out by TLC on silica gel (70-230 mesh).
Syn th esis of 2-Iod op h en ol Ester s.86 C6H4OC(O)-
CHdCH2-I-2. A suspension of 2-iodophenol (500 mg, 2.23
mmol), acryloyl chloride (205 mg, 2.23 mmol), and K2CO3 (1
g, 7,24 mmol) in acetone (10 mL) was refluxed for 3 h. After
addition of water (20 mL) and extraction with Et2O (3 × 5
mL), the organic phase was dried with anhydrous MgSO4 and
the solvents evaporated. The resulting crude ester was chro-
matographed through silica gel with 1.5:1 n-hexane/Et2O.
Evaporation of the eluents gave the ester as a colorless clear
oil. Yield: 550 mg, 90%. IR (cm-1): ν(CO) 1745. 1H NMR (200
3J CP ) 3.0 Hz), 144.03 (t, Pd-C, J CP ) 4.4 Hz), 134.71 (t, o-C
2
of PPh3, 2J CP ) 6.2 Hz), 131.60 (t, P-C, 1J PC ) 23.6 Hz), 129.93
(s, p-C of PPh3), 127.65 (t, m-C of PPh3, 3J CP ) 5.2 Hz), 124.52,
120.03 (2 C), 114.31 (s, C6H4 CH). 31P{1H} NMR (121 MHz,
CDCl3; ppm): 22.84. Anal. Calcd for C42H35IOP2Pd: C, 59.28;
H, 4.15. Found: C, 58.92; H, 3.98.
tr a n s-[P d {C6H4[OC(O)Me]-2}I(P P h 3)2] (1b). “Pd(dba)2”
(240 mg, 0.42 mmol), PPh3 (230 mg, 0.88 mmol), and the
corresponding 2-iodophenyl ester (131 mg, 0.5 mmol) were
mixed in dry degassed toluene (10 mL) and stirred for 4 h.
After evaporation of the solvent and extraction of the residue
with CH2Cl2 (10 + 2 × 3 mL), the combined organic extracts
were filtered over anhydrous MgSO4. The resulting solution
was evaporated to approximate 2 mL. Purification by chro-
matography through silica gel with 1:1.5 Et2O/n-hexane gave
a solid, which was recrystallized from CH2Cl2/n-hexane to give
1b as a white powder. Yield: 138 mg, 42%. Mp: 308 °C dec.
IR (cm-1): ν(CO) 1760. 1H NMR (200 MHz, CDCl3; ppm):
7.62-7.51 (m, PPh3, 12H), 7.34-7.19 (m, PPh3, 18H), 6.48 (d,
3
MHz, CDCl3; ppm): 7.85 (d, C6H4, 1 H, J HH ) 9.6 Hz), 7.37
3
3
(dd, C6H4, 1H, J HH ) 9.6 Hz, J HH ) 7.3 Hz), 7.12 (d, C6H4,
3
3
3
3
1H, J HH ) 9.6 Hz), 7.00 (dd, C6H4, 1H, J HH ) 7.3 Hz,
C6H4, 1H, J HH ) 8.0 Hz), 6.39 (dd, C6H4, 1H, J HH ) 8.0 Hz,
3J HH ) 9.3 Hz), 6.80 (dd, vinyl H (trans), 1H, J HH ) 18.0 Hz,
3
3J HH ) 7.6 Hz), 6.23 (d, C6H4, 1H, J HH ) 7.6 Hz), 6.01 (dd,
3
2J HH ) 1.3 Hz), 6.36 (dd, vinyl H, 1H, J HH ) 18.0 Hz, J HH
)
)
3
3
3
3
C6H4, 1H, J HH ) 8.0 Hz, J HH ) 7.6 Hz), 2.22 (s, Me, 3H).
3
2
13C{1H} NMR (50 MHz, CDCl3; ppm): 168.70 (s, CdO), 151.22,
12.0 Hz), 6.05 (dd, vinyl H (cis), 1H, J HH ) 12.0 Hz, J HH
1.3 Hz).
4
150.24 (s, C-O and C-Pd), 137.70 (d, p-C of PPh3, J CP ) 4.4
3
C6H4{OC(O)Me}-I-2. A suspension of 2-iodophenol (240 mg,
1.09 mmol), acetic anhydride (112 mg, 1.09 mmol), and
K2CO3 (3 g, 21,72 mmol) in acetone (10 mL) was stirred for 30
min. The solution was filtered through anhydrous MgSO4, and
the solvent was evaporated. The resulting crude ester was
chromatographed through silica gel with 1.5:1 n-hexane/Et2O.
Evaporation of the eluents gave the ester as a colorless clear
oil. Yield: 214 mg, 75%. IR (cm-1): ν(CO) 1785. 1H NMR (200
Hz), 134.88 (t, o-C of PPh3, J CP ) 6.5 Hz), 132.13 (t, C-P,
1J CP ) 23.5 Hz), 129.80 (s, CH C6H4), 127.65 (t, m-C of PPh3,
2J CP ) 5.0 Hz), 125.15, 122.87, 121.15 (s, CH C6H4), 21.84 (s,
Me). 31P{1H} NMR (121 MHz, CDCl3; ppm): 22.59. Anal. Calcd
for C44H37IO2P2Pd: C, 59.18; H, 4.16. Found: C, 59.19; H, 4.15.
tr a n s-[P d {C6H 4[OC(O)CH dCH 2]-2}I(P P h 3)2] (1c). The
same procedure as for 1b was used, starting from “Pd(dba)2”
(229 mg, 0.40 mmol), PPh3 (210 mg, 0.80 mmol), and the
corresponding 2-iodophenyl ester (140 mg, 0.49 mmol) to
prepare 1c as a yellow powder. Yield: 192 mg, 53%. Mp: 156
°C dec. IR (cm-1): ν(CO) 1726. 1H NMR (300 MHz, CDCl3;
ppm): 8.22-8.03 (m, PPh3, 12H), 7.86-7.69 (m, PPh3, 18H),
7.09 (d, vinyl H, 1H, J HH ) 15.5 Hz), 7.10 (d, C6H4, 1H, J HH
) 9 Hz), 7.00-6.77 (m, C6H4 and vinyl H, 3H), 6.53-6.48 (m,
C6H4 and vinyl H, 2H), 13C{1H} NMR (50 MHz, CDCl3; ppm):
164.32 (s, CdO), 151.23, 150.49 (C-O and C-Pd), 137.92 (s,
3
MHz, CDCl3; ppm): 7.82 (d, C6H4, 1H, J HH ) 7.8 Hz), 7.37
3
3
(dd, C6H4, 1H, J HH ) 8.4 Hz, J HH ) 7.8 Hz), 7.09 (d, C6H4,
1H, 3J HH ) 10.0 Hz), 7.00 (dd, C6H4, 1H, 3J HH ) 10.0 Hz, 3J HH
) 7.8 Hz), 2.36 (s, 3H, Me).
Syn th esis of Com p lexes. tr a n s-[P d (C6H4OH-2)I(P P h 3)2]
(1a ). “Pd(dba)2” (400 mg, 0.7 mmol), PPh3 (367 mg, 0.14 mmol),
and 2-iodophenol (175 mg, 0.8 mmol) were mixed in dry
degassed toluene (10 mL) and stirred for 4 h. After evaporation
of the solvent and extraction of the residue with CH2Cl2 (10 +
2 × 3 mL), the combined organic extracts were filtered over
anhydrous MgSO4. The resulting solution was concentrated
(2 mL), and a mixture of the complex and dba was precipitated
with n-hexane. Purification by chromatography through silica
gel with 1:1.5 Et2O/n-hexane gave a solid, which was recrys-
tallized from CH2Cl2/n-hexane to give 1a as a yellow powder.
3
3
2
C6H4, CH), 134.90 (t, o-C of PPh3, J CP ) 6.4 Hz), 132.11 (t,
i-C PPh3, J CP ) 23.6 Hz), 131.51 (dCH2), 129.75 (s, p-C of
PPh3), 128.91 (CHd), 127.62 (t, m-C of PPh3, J CP ) 5.2 Hz),
125.13, 122.93, and 121.04 (s, C6H4, CH). Anal. Calcd for
1
3
C
45H34IO2P2Pd: C, 59.78; H, 3.92. Found: C, 59.92; H, 3.80.
[P d (C6H4OH-2)I(bp y)] (2a ). “Pd(dba)2” (121 mg, 0.21
mmol), bpy (66 mg, 0.42 mmol), and o-iodophenol (110 mg, 0.5
mmol) were added to dry degassed toluene (7 mL). After 2.5 h
at 0 °C, the solvent was evaporated and the residue was
extracted with CH2Cl2 (10 + 2 × 3 mL). The combined extracts
were filtered over anhydrous MgSO4 and the resulting solution
concentrated (2 mL). Addition of Et2O precipitated a solid,
which was recrystallized from CH2Cl2/Et2O and dried in a
desiccator in vacuo over P2O5 to give 2a as an orange solid.
Yield: 54 mg, 54% (crude); 35 mg, 35% (recrystallized). Mp:
185 °C. IR (cm-1): ν(OH) 3422. 1H NMR (200 MHz, CDCl3;
(75) Delis, J . G. P.; Aubel, P. G.; Vanleeuwen, P.; Vrieze, K.;
Veldman, N.; Spek, A. L. J . Chem. Soc., Chem. Commun. 1995, 2233.
(76) Dupont, J .; Pfeffer, M. J . Chem. Soc., Dalton Trans. 1990, 3193.
(77) Wouters, J . M. A.; Klein, R. A.; Elsevier, C. J .; Zoutberg, M. C.;
Stam, C. H. Organometallics 1993, 12, 3864.
(78) Yamamoto, Y.; Yamazaki, H. Inorg. Chem. 1974, 13, 438.
(79) Campora, J .; Gutierrez, E.; Monge, A.; Palma, P.; Poveda, M.
L.; Ruiz, C.; Carmona, E. Organometallics 1994, 13, 1728.
(80) Tanase, T.; Fukushima, T.; Nomura, T.; Yamamoto, Y.; Koba-
yashi, K. Inorg. Chem. 1994, 33, 32.
(81) Yamamoto, Y.; Yamazaki, H. Synthesis 1976, 750.
(82) O’Sullivan, R. D.; Parkins, A. W. J . Chem. Soc., Chem. Commun.
1984, 1165.
(83) Gehrig, K.; Klaus, A. J .; Rys, P. Helv. Chim. Acta 1983, 66,
2603.
(84) Veya, P.; Floriani, C.; Chiesivilla, A.; Rizzoli, C. Organometallics
1993, 12, 4899.
(85) Albinati, A.; Pregosin, P. S.; Ru¨edi, R. Helv. Chim. Acta 1985,
68, 2046.
(86) Beckwith, A. L. J .; Gara, W. B. J . Chem. Soc., Perkin Trans.
1975, 795.
3
ppm): 9.61 (d, bpy, 1H, J HH ) 5.1 Hz), 8.12-8.00 (m, bpy,
3H), 7.52-7.42 (m, bpy and C6H4, 2H), 7.41-7.27 (m, bpy and
C6H4, 1H), 7.01-6.96 (m, bpy and C6H4, 1H), 7.66-7.21 (m,
bpy and C6H4, 1H), 6.97-6.93 (m, C6H4, 1H), 6.80-6.71 (m,
C6H4, 2H), 5.82 (s, OH, 1H). 13C{1H} NMR (50 MHz, CDCl3;
ppm): 156.81, 153.94, 152.86 (quaternary C), 150.48, 151.35,
138.87, 138.84 (bpy CH), 135.86, 126.99, 126.75, 125.35,
122.00, 121.61, 120.63, 113.86 (bpy CH and C6H4 CH). Anal.

Ortho-Palladated Phenol Derivatives
Organometallics, Vol. 20, No. 13, 2001 2707
Calcd for C16H13IN2OPd: C, 39.84; H, 2.72; N, 5.81. Found:
C, 39.89; H, 2.59; N, 5.88.
for 45 min. The solution was stirred for a further 1 h under
an atmosphere of CO and concentrated (2 mL), and addition
of n-hexane precipitated a solid, which was filtered and washed
with n-hexane (10 mL) to give 4a as a yellow solid. Yield: 69
mg, 84%. Mp: 194 °C dec. IR (cm-1): ν(CO) 1570. 1H NMR
[P d {C6H4[OC(O)Me]-2}I(bp y)] (2b). The same procedure
as for 1b was used, starting from “Pd(dba)2” (257 mg, 0.45
mmol), bpy (70 mg, 0.45 mmol), and the corresponding
2-iodophenyl ester (130 mg, 0.5 mmol) in toluene (7 mL) to
prepare 2b as a bright yellow powder. Yield: 148 mg, 63%.
(200 MHz, CDCl3; ppm): 9.72 (s, OH, 1H), 8.64 (d, C6H4
H
3
ortho to CdO, J HH ) 7.2 Hz, 1H), 7.61-7.58 (m, PPh3, 12H),
3
1
Mp: 120 °C dec. IR (cm-1): ν(CO) 1757. H NMR (200 MHz,
7.29-7.20 (m, PPh3, 18H), 6.97 (dd, C6H4, 1H, J HH ) 7.4 Hz,
3
3
3J HH ) 7.2 Hz), 6.01 (dd, C6H4, 1H, J HH ) 7.4 Hz, J HH ) 7.0
Hz), 6.94 (d, C6H4, 1H, 3J HH ) 8.5 Hz). 13C{1H} NMR (50 MHz,
CDCl3; ppm): 245.57 (s, CO), 156.75 (s, COH), 135.19 (t, C6H4
3
CDCl3; ppm): 9.64 (d, bpy, 1H, J HH ) 6.0 Hz), 8.10-7.97 (m,
3
bpy, 4H), 7.76 (d, bpy, 1H, J HH ) 4.0 Hz), 7.52-7.42 (m, bpy
and C6H4, 2H), 7.41-7.27 (m, bpy and C6H4, 1H), 7.01-6.96
(m, bpy and C6H4, 2H), 6.85-6.81 (m, C6H4, 1H), 2.21 (s, Me,
3H). 13C{1H} NMR (50 MHz, CDCl3; ppm): 170.83 (s, CdO),
155.50, 154.09, 153.93 (quaternary C), 153.18, 151.35 (bpy
C-H), 138.69, 137.64 (bpy C-H), 135.30 (quaternary C),
126.76, 126.38, 125.06, 124.50, 121.62, 121.57, 121.44 (C6H4
C-H and bpy C-H), 22.03 (Me). Anal. Calcd for C18H15IN2O2-
Pd: C, 41.21; H, 2.88; N, 5.34. Found: C, 41.18; H, 3.28; N,
5.10.
4
2
CH), J CP ) 2.4 Hz), 134.88 (t, o-C of PPh3, J CP ) 6.2 Hz),
1
133.55 (s, C6H4 CH), 131.09 (t, C-P, J CP ) 22.9 Hz), 130.30
(s, p-C of PPh3), 128.00 (t, m-C of PPh3, 3J CP ) 2.1 Hz), 125.27
(t, C(O)-Carom
,
3J PC ) 12 Hz), 118.39, 116.29 (s, C6H4 CH).
31P{1H} NMR (121 MHz, CDCl3; ppm): 18.88. Anal. Calcd for
C
43H35IO2P2Pd: C, 58.76; H, 4.01. Found: C, 58.09; H, 4.00.
[P d {C(O)C6H4OH-2}I(bp y)] (5a ). CO was bubbled through
a solution of 2a (80 mg, 0.17 mmol) in CH2Cl2 (10 mL) for 30
min. The solution was stirred for a further 1 h under an
atmosphere of CO and concentrated (2 mL), and addition of
Et2O precipitated a solid, which was filtered and washed with
Et2O (10 mL) to give 5a as a red-orange solid. Yield: 78 mg,
92%. Mp: 268 °C dec. IR (cm-1): ν(CO) 1596. 1H NMR (200
MHz, DMSO-d6; ppm): 10.25 (s, OH, 1H), 8.64-8.58 (m, bpy
and C6H4, 3H), 8.30-8.25 (m, bpy and C6H4, 3H), 7.80-7.61
(m, bpy and C6H4, 3H), 7.30-7.27 (m, C6H4 or bpy H, 1H),
6.81-6.73 (m, C6H4 or bpy H, 2H). 13C{1H} NMR (50 MHz,
[P d {C6H4[OC(O)Me-2]}(bp y)P P h 3)]OTf (3b). To a sus-
pension of Tl(OTf) (OTf ) OSO2CF3; 23.0 mg, 0.065 mmol) in
CH2Cl2 (7 mL) were added complex 1b (55 mg, 0.061 mmol)
and, 2-3 min later, bpy (9.53 mg, 0.061 mmol), and the
mixture was stirred for 14 h. The resulting suspension was
filtered over Celite, and the filtrate was concentrated to
dryness to give a bright yellow solid, which was finally
recrystallized from CH2Cl2/Et2O to give 3b. Yield: 38 mg, 77%.
Mp: 161 °C. IR (cm-1): ν(CO) 1746, ν(SO3) 1268, 1152. 1H
NMR (200 MHz, CDCl3; ppm): 8.78-8.70 (m, aromatic H of
bpy, 2H), 8.22-8.14 (m, aromatic H of bpy, 2H), 7.63-7.27 (m,
aromatic H of PPh3, bpy, 20H), 7.20-6.3 (m, aromatic H of
bpy and/or C6H4, 5H), 2.16 (s, Me, 3H). 13C{1H} NMR (50 MHz,
CDCl3; ppm): 169.39 (CdO), 155.71, 155.40, 151.70 (quater-
CDCl3; ppm): not sufficiently soluble. Anal. Calcd for C17H13
-
IN2O2Pd: C, 39.99; H, 2.57; N 5.49. Found: C, 39.86; H, 2.42;
N, 5.49.
[P d {C(O)C6H4OH-2}(bp y)P P h 3)]OTf (6a ). To a suspen-
sion of Tl(OTf) (25.3 mg, 0.072 mmol) in CH2Cl2 (7 mL) was
added complex 4a (63 mg, 0.072 mmol). After 5 min, bpy (11.2
mg, 0.072 mmol) was added and the resulting mixture stirred
for 6 h. The suspension was filtered over Celite to give a yellow
solution, which was concentrated (2 mL). Addition of n-hexane
gave a solid, which was recrystallized from CH2Cl2/n-hexane
to give 6a as a bright yellow powder. Yield: 49 mg, 86%. Mp:
121 °C dec. IR (cm-1): ν(CO) 1600, ν(SO3) 1266, 1148. 1H NMR
(300 MHz, CDCl3; ppm): 10.08 (s, OH, 1H), 8.81 (d, bpy H,
2
nary C), 150.82, 150.38 (aromatic CH), 145.22 (d, Pd-C, J PC
) 12 Hz), 141.44, 141.33, 135.41, 135.34 (aromatic CH), 134.42
(d, o-C of PPh3, 2J PC ) 11.9 Hz), 131.88 (d, p-C of PPh3, 4J PC
)
2.6 Hz), 129.18, 129.29 (d, m-C of PPh3, 3J PC ) 11.1 Hz), 126.73,
126.48, 126.20, 125.78, 124.79, 124.13, 122.84 (aromatic CH).
31P{1H} NMR (121 MHz, CDCl3; ppm): 33.11. Anal. Calcd for
C
37H30F3N2O5PPdS: C, 54.93; H, 3.74; N, 3.46; S, 3.96.
Found: C, 54.68; H, 3.50; N, 3.24; S, 3.69.
3
3
2H, J HH ) 8.4 Hz), 8.61 (d, C6H4 ortho to CdO, 1H, J HH
)
[P d (C6H4{OC(O)C2H3-2})(bp y)P P h 3]OTf (3c). The same
procedure as for 3b was used, starting from Tl(OTf) (27.5 mg,
0.080 mmol) in CH2Cl2 (7 mL) and 1c (70 mg, 0.078 mmol), to
prepare yellow 3c, except that concentrating the filtrate to
dryness led to a yellow foam, which was stirred with Et2O for
1 h to remove some PPh3; Et2O was decanted, and the solid
was dried in vacuo. Yield: 57 mg, 91.3%. Mp: 158 °C. IR
3
3
8.1 Hz), 8.22 (dd, bpy H, 2H, J HH ) 8.1 Hz, J HH ) 8.1 Hz),
7.68-7.62 (m, aromatic H, 7H), 7.57-7.49 (m, aromatic H, 3H),
7.46-7.37 (m, aromatic H, 7H), 7.32-7.26 (m, aromatic H, 3H),
3
3
6.87 (dd, C6H4, 1H, J HH ) 6.0 Hz, J HH ) 6.3 Hz), 6.35 (d,
C6H4, 1H, J HH ) 8.4 Hz). 13C{1H} NMR (50 MHz, CDCl3;
3
ppm): 235.98 (CO), 157.54 (quaternary C, COH), 155.01
(quaternary C), 150.17, 141.69 (CH, bpy), 135.59, 135.36 (CH,
bpy), 134.25 (d, o-C of PPh3, 2J PC ) 12.5 Hz), 132.01 (d, p-C of
1
(cm-1): ν(CO) 1734, ν(SO3) 1276, ν(SO3) 1152. H NMR (300
MHz, CDCl3; ppm): 9.79-9.73 (m, aromatic H of bpy, 2H),
8.22-8.16 (m, aromatic H of bpy, 2H), 7.75-7.21 (m, aromatic
H of PPh3, bpy and C6H4, 21H), 7.05-6.95 (m, aromatic H of
4
3
PPh3, J PC ) 2.2 Hz), 129.29(d, m-C of PPh3, J PC ) 11.1 Hz),
128.61, 128.37, 126.88, 125.05 (aromatic CH), 122.05 (quater-
nary C), 119.81, 117.14 (C6H4 CH). The signal of P-C is
probably obscured by the signals of m-C of PPh3. 31P{1H} NMR
(121 MHz, CDCl3; ppm): 29.44. Anal. Calcd for C36H28F3N2O5-
PPdS: C, 54.39; H, 3.55; N, 3.52; S, 4.03. Found: C, 54.78; H,
3.48; N, 3.24; S, 4.25.
3
3
bpy and/or C6H4, 2H), 6.78 (dd, C6H4, 1H, J HH ) 7.4 Hz, J HH
3
) 7.0 Hz), 6.94 (d, phenyl CH, 1H, J HH ) 8.5 Hz), 6.30 (d,
3
terminal vinyl H (trans), J HH ) 16.0 Hz, 1H), 6.40 (dd, vinyl
3
3
H, 1H, J HH ) 16.0 Hz, J HH ) 10.0 Hz), 6.31 (d, vinyl H (cis),
3
3
1H, J HH ) 12.0 Hz), 6.05 (d, terminal vinyl H (cis), 1H, J HH
) 12.0 Hz). 13C{1H} NMR (50 MHz, CDCl3; ppm): 164.59
(CdO), 155.71, 155.38, 151.68 (quaternary C), 150.90, 150.34
tr a n s-[P d {C(dNXy)C6H4OH-2}I(CNXy)2] (7a ). Meth od
A. “Pd(dba)2” (240 mg, 0.42 mmol) and XyNC (115 mg, 0.85
mmol) were added to dry degassed toluene (10 mL) at 0 °C
and stirred under N2. After 5 min, C6H4OH-I-2 (300 mg, 1.36
mmol) was added and the reaction mixture stirred for a further
4 h and for 20 h more at room temperature. The resulting
suspension was evaporated to dryness, the residue was
extracted with CH2Cl2, and the extract was filtered over
anhydrous MgSO4. The orange filtrate was concentrated to
2-3 mL, and Et2O was added. After a few minutes of stirring
complex 7a precipitated as a pale yellow solid. Diffraction-
quality crystals were grown by slow diffusion of Et2O into a
CH2Cl2 solution of 7a . Yield: 130 mg, 64% (calculated assum-
ing eqs 1-3; see below).
2
(CH, bpy), 145.40 (d, Pd-C, J PC ) 11.9 Hz), 143.29, 141.46,
141.32, 135.45, 135.38 (CH, bpy), 134.45 (d, o-C of PPh3, J PC
2
) 12 Hz), 132.60 (dCH2), 132.15 (CH), 132.00 (dCH), 131.87
4
(d, p-C of PPh3, J PC ) 3 Hz), 129.17 (P-C; one part of the
doublet, the other part might be below the next PPh3 m-C
signal), 129.80 (d, m-C of PPh3, 3J PC ) 11.0 Hz), 128.61, 128.37,
128.11, 126.71, 126.43, 126.23, 125.89, 124.78, 124.06, 122.80
(aromatic CH). 31P{1H} NMR (121 MHz, CDCl3; ppm): 33.82.
Anal. Calcd for C38H30F3N2O5PPdS: C, 55.59; H, 3.68; N, 3.41;
S, 3.91. Found: C, 55.18; H, 3.70 N, 3.73; S, 4.20.
tr a n s-[P d{C(O)C6H4OH-2}I{P P h 3)2] (4a). CO was bubbled
through a solution of 1a (80 mg, 0.09 mmol) CH2Cl2 (10 mL)

2708 Organometallics, Vol. 20, No. 13, 2001
Vicente et al.
Met h od B. To a solution of 2a (60 mg, 0.12 mmol) in
CH2Cl2 (10 mL) at 0 °C was added XyNC (44 mg, 0.37 mmol),
and the mixture was stirred for 3 h. The solution was con-
centrated (2-3 mL), and n-hexane was added to give a suspen-
sion. The solid was filtered off and washed with n-hexane (10
mL) to give 7a as a pale yellow powder. Yield: 50 mg, 56%.
Mp: 195 °C dec. IR (cm-1): ν(CtN) 2176, ν(CdN) 1556. 1H
NMR (200 MHz, CDCl3; ppm): 13.66 (s, OH, 1H), 8.61 (d, H
of n-hexane precipitated a solid, which was filtered off, washed
with a further 10 mL of n-hexane, and air-dried to give 7b*
as a pale yellow powder. Yield: 37 mg, 60%. Mp: 144 °C dec.
1
IR (cm-1): ν(CtN) 2190, ν(CO) 1758, ν(CdN) 1636. H NMR
(300 MHz, CDCl3; ppm): 7.59-7.56 (m, H of C6H4 ortho to
CdN, 1H), 7.27-7.22 (m, C6H4, 2H), 6.98 (m, H of C6H4 ortho
t
to OH, 1H), 2.25 (s, Me, 3H), 1.55 (s, Bu, 9H), 1.47 (s, 2 ×
tBu, 18H). 13C{1H} NMR (50 MHz, CDCl3; ppm): 173.17
(CdN), 168.97 (CdO), 144.48 (COH), 136.01 (quaternary C),
131.45, 128.18, 125.54, 123.51 (CH), 57.97, 56.60 (quaternary
3
of C6H4 ortho to CdN, 1H, J HH ) 7.0 Hz), 7.38-7.19 (m,
aromatic H of C6H4 and isonitrile, 3H), 7.08-6.96 (m, aromatic
H of C6H4 and isonitrile, 9H), 2.20 (s, Me, 12H), 2.16 (s, Me,
6H). 13C{1H} NMR (75 MHz, CDCl3; ppm): 188.19 (CdN),
158.10 (COH), 147.79 (quaternary C, -NC), 136.70 (CH),
136.04 (quaternary C, C-Me), 131.75 (CH), 130.20 (CH),
128.25 (CH), 128.08 (CH), 124.60 (CH), 118.38 (CH), 116.21
(aromatic CH), 18.85, 18.57 (Me). Anal. Calcd for C33H32IN3-
OPd: C, 55.05; H, 4.48; N, 5.84. Found: C, 55.20; H, 4.42; N,
5.78.
C of tBu), 30.00, 29.78 (tBu), 21.34 (Me). Anal. Calcd for C23H34
-
IN3O2Pd: C, 44.71; H, 5.55; N, 6.80. Found: C, 44.54; H, 5.49;
N, 6.77.
[P d {C(dNXy)C6H4OH-2}I(bp y)] (8a ). XyNC (25 mg, 0.19
mmol) was added to a solution of 2a (100 mg, 0.21 mmol) in
CH2Cl2 (10 mL). The mixture was stirred for 8 h, the resulting
suspension filtered, and the solid washed with a mixture of
CH2Cl2 (10 mL) and Et2O (5 mL) to give 8a as a yellow solid.
Yield: 70 mg, 54%. Mp: 248 °C dec. IR (cm-1): ν(CdN) 1536.
NMR: not sufficiently soluble. Anal. Calcd for C25H22IN3OPd:
C, 48.92; H, 3.61; N 6.85. Found: C, 47.21; H, 3.74; N, 6.87.
The insolubility of 8a prevented recrystallization.
tr a n s-[P d {C(dNtBu )C6H4OH-2}I(CNtBu )2] (7a *). Method
A for 7a was used, starting from “Pd(dba)2” (240 mg, 0.42
mmol), tBuNC (70 mg, 0.84 mmol), and C6H4(OH)-I-2 (111 mg,
0.504 mmol). Reaction time: 1 h at 0 °C and 2 h at room
temperature. The CH2Cl2 solution was concentrated, and a
large excess of n-hexane was added. The solvent was decanted
and the solid dried in vacuo to give 7a * as a bright yellow solid.
Yield: 130 mg, 81% (calculated assuming eqs 1-3; see below).
Mp: 141 °C dec. IR (cm-1): ν(CtN) 2198, ν(CdN) 1572. 1H
NMR (300 MHz, CDCl3; ppm): 15.89 (vb s, OH, 1H), 8.46 (d,
[P d {C(dNtBu )C6H4OH-2}I(bp y)] (8a *). tBuNC (9 mg, 0.11
mmol) was added to a solution of 2a (63 mg, 0.11 mmol) in
CH2Cl2 (10 mL) at 0 °C and the mixture stirred for 3 h. The
solvent was evaporated, the residue dissolved in CH2Cl2 (2
mL), and this solution chromatographed through silica gel with
1.5:1 CH2Cl2/Et2O as eluant. The yellow band was collected
and extracted with acetone. Evaporation of the solvent and
recrystallization of the residue from CH2Cl2/Et2O gave 8a * as
a yellow-orange powder. Yield: 41 mg, 66%. Mp: 256 °C dec.
IR (cm-1): ν(CdN) 1598. 1H NMR (200 MHz, acetone-d6;
3
H of C6H4 ortho to CdN, 1H, J HH ) 9.0 Hz), 7.20 (dd, C6H4,
3
3
1H, J HH ) 7.5 Hz, J HH ) 9.0 Hz), 6.83 (m, C6H4, 1H), 6.79
3
t
(d, H of C6H4 ortho to OH, 1H, J HH ) 7.5 Hz), 1.63 (s, Bu,
9H), 1.37 (s, 2xtBu, 18H). 13C{1H} NMR (50 MHz, CDCl3;
ppm): 182.03 (CdN), 159.56 (COH), 136.57 (CH, C6H4), 130.56
(CH, C6H4), 128.99, 127.53 (quaternary C and terminal
tBuNC), 117.01 (CH, C6H4), 116.13 (CH, C6H4), 65.80, 57.02
3
ppm): 13.90 (s, OH, 1 H), 9.50 (d, bpy, 1H, J HH ) 5.3 Hz),
3
3
9.06 (dd, bpy, 1H, J HH ) 8.3 Hz, J HH ) 8.0 Hz), 8.61-8.09
(m, bpy, 5H), 7.83-7.66 (m, bpy, 2H), 7.22-7.00 (m, bpy and
C6H4, 2H), 6.66-6.58 (m, C6H4, 2H), 1.68 (s, 9H, tBu). 13C{1H}
NMR: not sufficiently soluble. Anal. Calcd for C21H22IN3OPd:
C, 44.59; H, 3.92; N 7.43. Found: C, 45.21; H, 4.01; N, 7.62.
[P d {C(dNXy)C6H4[OC(O)Me]-2}I(bp y)] (8b). XyNC (22
mg, 0.17 mmol) was added to a solution of 2b (87 mg, 0.17
mmol) in CH2Cl2 (10 mL) at 0 °C. The resulting solution was
slowly warmed to room temperature and stirred for a further
14 h. The solution was concentrated (2 mL), and addition of
n-hexane caused the precipitation of a yellow-orange powder,
which was purified by chromatography through silica gel using
1.5:1 CH2Cl2/Et2O. Diffraction-quality crystals were grown by
slow diffusion of Et2O into a CH2Cl2 solution of 8b. Yield: 77
mg, 69%. Mp: 215 °C dec. IR (cm-1): ν(CO) 1768, ν(CdN) 1614.
1H NMR (300 MHz, CDCl3; ppm): 9.42 (d, bpy, 3J HH ) 7.0 Hz,
(quaternary C of tBu), 31.06, 29.65 (Me). Anal. Calcd for C21H32
-
IN3OPd: C, 43.80; H, 5.60; N, 7.30. Found: C, 43.76; H, 5.60
N, 7.35.
tr a n s-[P d {C(dNXy)C6H4OC(O)Me-2}I(CNXy)2]
(7b).
Method A for 7a was used, starting from “Pd(dba)2” (240 mg,
0.42 mmol), XyNC (165 mg, 1.26 mmol), and 2-MeCO2C6H4I
(132 mg, 0.50 mmol). Reaction time: 4 h at 0 °C and 3 days at
room temperature. The CH2Cl2 solution was concentrated and
n-hexane added, causing the precipitation of a green powder.
A concentrated CH2Cl2 solution was subjected to preparative
thin-layer chromatography using 1:1 Et2O/n-hexane through
silica gel. The pink fraction was collected and extracted with
CH2Cl2. This solution was concentrated (2 mL), n-hexane was
added very slowly to form two layers, and the flask was stored
at -15 °C. Over 3 days, complex 7b precipitated as a yellow
solid that did not need further purification. Diffraction-quality
crystals were grown by slow diffusion of n-hexane into a
CH2Cl2 solution of 7b. Yield: 182 mg, 57%. Mp: 213 °C. IR
(cm-1): ν(CtN) 2182, ν(CO) 1766, ν(CdN) 1586. 1H NMR (300
MHz, CDCl3; ppm): 8.61 (d, H of C6H4 ortho to CdN, 1H, 3J HH
) 7.5 Hz), 7.42-6.94 (m, aromatic H of C6H4 and isonitrile,
9H), 7.08-6.96 (m, aromatic H of C6H4 and isonitrile, 3H), 2.33
(s, Me, 3H), 2.19 (s, Me, 12H), 2.13 (s, Me, 6H).13C{1H} NMR
(75 MHz, CDCl3; ppm): 172.30 (CdN), 169.71 (CdO), 150.16,
147.42, 134.04, 137.20 (quaternary C), 135.80 (CH), 132.15,
131.95 (quaternary C), 130.61 (CH), 130.15 (quaternary C),
129.69, 129.18, 128.67, 127.10, 126.19 (CH), 125.34 (quater-
nary C), 124.18, 122.79, 122.44 (CH), 22.00 (MeC(O)), 18.78,
18,55, 18,43 (Me). Anal. Calcd for C35H34IN3O2Pd: C, 55.17;
H, 4.50; N, 5.51. Found: C, 55.40; H, 4.38; N, 5.99.
3
3
1H), 9.27 (dd, bpy, 1H, J HH ) 7.8 Hz, J HH ) 8.1 Hz), 8.55 (d,
3
aromatic H, J HH ) 5.7 Hz, 1H), 8.01-7.90 (m, aromatic H,
4H), 7.45-6.62 (m, aromatic H, 8H), 2.14 (b s, Me, 6H), 2.10
(s, Me, 3H). 13C{1H} NMR: not sufficiently soluble. Anal. Calcd
for C27H24IN3O2Pd: C, 49.45; H, 3.69; N 6.41. Found: C, 49.96;
H, 3.55; N, 6.33.
[P d {C(dNXy)C6H4OH-2}(CNXy)(bp y)]OTf (9a ). Complex
7a (46 mg, 0.064 mmol) was added to a suspension of Tl(OTf)
(25 mg, 0.071 mmol) in CH2Cl2 (7 mL). After 5 min, bpy (11
mg, 0.011 mmol) was added and the mixture stirred for a
further 14 h. The resulting suspension was filtered, the filtrate
was concentrated (1 mL), and an excess of Et2O was added to
precipitate the pale yellow, flocculent complex 9a . Yield: 43
mg, 74%. Mp: 185 °C dec. IR (cm-1): ν(CtN) 2158, ν(CdN)
1564, ν(SO3) 1268, 1090. 1H NMR (200 MHz, CDCl3; ppm):
13.36 (s, OH, 1H), 8.83-8.80 (m, aromatic H, 2H), 8.63 (dd,
aromatic H, 1H, 3J HH ) 7.8 Hz, 3J HH ) 7.8 Hz), 8.36-8.26 (m,
aromatic H, 3H), 8.09 (d, aromatic H, 1H, 3J HH ) 4.8 Hz), 7.70
tr a n s-[P d {C(dNtBu )C6H4OC(O)Me-2}I(CNtBu )2] (7b*).
To a solution of 2b (50 mg, 0.10 mmol) in CH2Cl2 (10 mL) at
t
3
3
0 °C was added BuNC (24 mg, 0.30 mmol) (the initially yellow
(dd, aromatic H, 1H, J HH ) 6.7 Hz, J HH ) 6.1 Hz), 7.50-
6.91 (m, aromatic H, 10H), 2.19 (s, Me, 6H), 1.99 (s, Me, 3H),
1.85 (s, Me, 3H). 13C{1H} NMR (50 MHz, CDCl3; ppm): 188.75
(CdN), 159.35, 156.60, 153.32 (quaternary C), 150.65 (CH),
solution immediately became pale yellow), and the mixture
was stirred for a further 3 h. After 3 h the clear reaction
mixture was evaporated to approximately 2-3 mL; addition

Ortho-Palladated Phenol Derivatives
Organometallics, Vol. 20, No. 13, 2001 2709
150.11, 147.67 (quaternary C), 142.51, 142.22 (CH), 135.72
(quaternary C), 135.39, 133.09, 131.15, 128.56, 128.27, 128.24,
127.32, 125.19 (CH), 125.14, 122.74 (quaternary C), 119.21,
117.00 (CH),18.56 (Me),15.23 (Me).Anal.Calcd for C35H31F3N4O4-
SPd: C, 54.80; H, 4.07; N, 7.30; S, 4.18. Found: C, 55.03; H,
4.32; N, 7.35; S, 3.68.
ppm): 11a * decomposed in CDCl3 solution after 1 h. Anal.
Calcd for C23H32F3N3O5PdS: C, 44.13; H, 5.15; N, 6.71; S,5.12.
Found: C, 43.96; H, 5.31; N, 6.93; S, 5.29.
[P d {K2(C,O)-µ2(O)-C(dNXy)C6H4O-2}(CNXy)]4 (12). To a
yellow suspension of 7a (25 mg, 0.035 mmol) in acetone (10
mL) was added Pd(OAc)2 (4 mg, 0.017 mmol) at room temper-
ature. After 2.5 h, the mixture was evaporated to dryness,
the residue was dissolved in CH2Cl2 (2 mL), and Et2O was
added to precipitate a solid that was filtered, washed with
n-hexane (5 mL), and finally air-dried to give 12 as a yellow
solid. Diffraction-quality crystals were grown by slow diffu-
sion of n-hexane into a very dilute solution of 12 in CH2Cl2.
Yield: 13 mg, 81%. Mp: 154 °C dec. IR (cm-1): ν(CtN) 2184,
tr a n s-[P d {C(O)C6H4OH-2}I(CNXy)2] (10a ). CO was bub-
bled through a solution of 2a (60 mg, 0.12 mmol) in CH2Cl2
(10 mL) for 40 min. The resulting deep orange solution was
stirred for a further 30 min under an atmosphere of CO. The
flask was then cooled in an ice bath, and XyNC (33 mg, 0.25
mmol) was added, causing a change of color of the reaction
mixture from orange to yellow. After 3 h of further stirring at
0 °C, the solution was concentrated (2 mL) and Et2O was
added. The resulting suspension was filtered and the solid
washed with Et2O (10 mL) to give 10a as a red-orange powder.
Yield: 62 mg, 84%. Mp: 129 °C dec. IR (cm-1): ν(CtN) 2182,
1
ν(CdN) 1642. H NMR (300 MHz, CDCl3; ppm): 7.83 (d, H of
C6H4 ortho to CdN, 4H, 3J HH ) 7.8 Hz), 7.29-7.13 (m, aromatic
H of isonitrile, 12 H), 6.80-6.71 (m, aromatic H, 12 H), 6.47
3
3
(dd, C6H4, 4H, J HH ) 7.5 Hz, J HH ) 7.2 Hz), 6.32 (d, C6H4
1
3
3
ν(CO) 1626. H NMR (200 MHz, CDCl3; ppm): 10.79 (s, OH,
1-H, 4H, J HH ) 8.4 Hz), 6.22 (dd, C6H4, 4H, J HH ) 7.2 Hz,
3J HH ) 7.5 Hz), 2.22 (s, Me, 24H), 2.20 (s, Me, 24H). 13C{1H}
NMR (50 MHz, CDCl3; ppm): 169.75 (CdN), 151.87 (COH),
134.46 (CH), 132.38 (PdCNR′), 132.05 (CH), 129.05 (CH),
128.19 (quaternary C, Pd-C(dNXy)C6H4-), 127.61, 127.42
(CH), 126.89 (quaternary C, C-Me), 126.76, 123.12, 116.90,
115.36 (CH), 19.30, 18.52 (Me). Anal. Calcd for C96H88N8O4-
Pd4: C, 62.55; H, 4.81; N, 6.08. Found: C, 63.23; H, 4.86; N,
5.76.
1H), 8.75 (d, H of C6H4 ortho to CdO, 3J HH ) 7.1 Hz, 1H), 7.44
3
3
(dd, aromatic H of C6H4 or isonitrile, 1H, J HH ) 7.1 Hz, J HH
) 7.2 Hz), 7.26-7.04 (m, C6H4 and isonitrile H, 7H), 6.91 (d,
3
C6H4, 1H, J HH ) 8.2 Hz), 2.29 (s, Me, 12H). 13C{1H} NMR
(50 MHz, CDCl3; ppm): 230.03 (CdO), 156.25 (COH),
137.78, 136.20, 135.00, 130.28 (CH), 128.43 (quaternary C),
119.80, 116.67 (CH C6H4), 18.51 (Me). Anal. Calcd for C25H24
-
IN2OPd: C, 48.65; H, 3.76; N 4.54. Found: C, 48.10; H, 3.63;
N, 4.62.
The complex [PdI2(CNXy)2] is obtained on workup of the
mother liquors from 12. Yield: 9 mg, 83%. Mp: 129 °C dec.
IR (cm-1): ν(CtN) 2194. 1H NMR (300 MHz, CDCl3; ppm):
7.16 (m, H ortho to CMe, 4 H), 7.13 (m, H meta to CMe, 2 H),
2.57 (s, Me, 12H). Anal. Calcd for C18H18I2N2Pd: C, 34.73; H,
2.91; N, 4.50. Found: C, 35.15; H, 2.86; N, 4.66.
X-r a y Str u ctu r e Deter m in a tion s. A summary of X-ray
data is presented in Table 1.
Da ta Collection . Data were recorded at low temperature
using Mo KR radiation. Appropriate absorption corrections
(multiscan for area detector data, ψ-scan for others) were
applied.
tr a n s-[P d {C(O)C6H4OH-2}I(CNtBu )2] (10a *). Complex
10a * was similarly prepared from 2a (70 mg, 0.15 mmol) and
tBuNC (36 mg, 0.44 mmol). Orange-brown 10a * was precipi-
tated with n-hexane. Yield: 59 mg, 78%. Mp: 128 °C dec. IR
(cm-1): ν(CtN) 2206, ν(CO) 1618. 1H NMR (200 MHz, CDCl3;
ppm): 10.78 (s, OH, 1H), 8.54 (d, H of C6H4 ortho to CdO,
3
3
3J HH ) 8.0 Hz, 1H), 7.43 (dd, C6H4, 1H, J HH ) 8.0 Hz, J HH
)
)
3
7.1 Hz), 7.23-7.03 (m, C6H4, 1H), 6.89 (d, C6H4, 1H, J HH
8.2 Hz), 1.40 (s, Bu, 18H). 13C (1H) NMR (50 MHz, CDCl3;
ppm): 230.93 (CdO), 156.20 (COH), 137.61 (CH C6H4), 135.13
(quaternary C), 134.58 (CH C6H4), 127.80, 125.85, 123.92
(quaternary C), 119.44, 116.49 (CH C6H4), 58.36 (quaternary
C of tBu), 29.72 (tBu). Anal. Calcd for C17H23INO2Pd: C, 40.46;
H, 4.59; N 5.55. Found: C, 40.27; H, 4.07; N, 5.33.
t
Str u ctu r e Refin em en t. Structures were refined anisotro-
pically on F2 using the program SHELXL-97 (G. M. Sheldrick,
University of Go¨ttingen, Go¨ttingen, Germany). Hydrogen
atoms were refined as follows: OH, restrained in 7a , rigid
group in 5a , 12; methyls, riding in solvent of 9a , otherwise
rigid; all others riding.
[P d {C(O)C6H4OH-2}(CNXy)3]OTf (11a ). CO was bubbled
through a solution of 2a (64 mg, 0.13 mmol) in CH2Cl2 (10
mL) for 30 min, and the resulting deep orange solution was
1
stirred for a further /2 h under an atmosphere of CO. The flask
Sp ecia l F ea tu r es. The isonitrile C31-C38 in compound
7b is disordered over two sites with occupation factors 0.64/
0.36. Compound 9a crystallizes with one ether molecule, which
is well-ordered. The structure of 12 contained badly resolved
residual electron density disordered about the 4-fold axis. This
was arbitrarily refined as two carbon sites. Quoted values for
M and related parameters of 12 do not include solvent.
was cooled to 0 °C, XyNC (139 mg, 1.06 mmol) was added
(causing decolorization), and the mixture was stirred for 15
min. Tl(OTf) (50 mg, 0.14 mmol) was added, and the resulting
suspension stirred for 4 h more at 0 °C and filtered over Celite.
The filtrate was concentrated (2 mL), and addition of Et2O
precipitated a solid, which was filtered and washed with Et2O
(10 mL) to give 11a as a white powder. Yield: 58 mg, 57%.
Mp: 97 °C dec. IR (cm-1): ν(CtN) 2186, ν(CO) 1622. 1H NMR
(200 MHz, CDCl3; ppm): 10.31 (s, OH, 1H), 8.37 (d, H of
3
Resu lts a n d Discu ssion
C6H4 ortho to CdO, J HH ) 6.6 Hz, 1H), 7.43 (dd, aromatic H
of C6H4 or isonitrile, 1H, 3J HH ) 8.4 Hz, 3J HH ) 7.6 Hz), 7.26-
6.96 (m, C6H4 and isonitrile H, 11H), 2.25 (b s, Me, 18H). 13C
(1H) NMR (50 MHz, CDCl3; ppm): 11a decomposed in CDCl3
solution after 1 h. Anal. Calcd for C35H32F3N3O5PdS: C, 54.59;
H, 4.19; N, 5.46; S, 4.16. Found: C, 54.26; H, 4.26; N, 5.68; S,
4.01.
Syn t h esis of Com p lexes 1-3. 2-Iodophenol and
its derivatives 2-ROC6H4I, where R ) C(O)Me, C(O)-
CHdCH2, react with [Pd2(dba)3]‚dba (“Pd(dba)2”) in the
presence of neutral ligands to give the products of the
oxidative addition reactions. Thus, the reaction in the
presence of 2 equiv of PPh3 results in the formation of
trans-[Pd(C6H4OR-2)I(PPh3)2] (R ) H (1a ), C(O)Me (1b),
C(O)CHdCH2 (1c)) (Scheme 1). Similarly, the use of
2,2′-bipyridine (bpy) led to complexes [Pd(C6H4OR-2)I-
(bpy)] (R ) H (2a ), C(O)Me (2b)), although the reaction
of C6H4[OC(O)CHdCH2]-I-2 with “Pd(dba)2” in the
presence of bpy failed to give the corresponding complex.
Such a procedure has been shown to be useful for the
synthesis of organopalladium complexes containing
[P d {C(O)C6H4OH-2}(CNtBu )3]OTf (11a *). Complex 11a *
t
was similarly prepared from 2a (64 mg, 0.13 mmol), BuNC
(90 mg, 1.06 mmol), and Tl(OTf) (50 mg, 0.14 mmol). White
11a * was precipitated by addition of n-hexane. Yield: 62 mg,
1
71%. Mp: 88 °C dec. IR (cm-1): ν(CtN) 2224, ν(CO) 1586. H
NMR (200 MHz, CDCl3; ppm): 10.42 (s, OH, 1H), 8.24 (d, H
of C6H4 ortho to CdO, 3J HH ) 7.5 Hz, 1H), 7.43 (dd, C6H4, 1H,
3
3
3J HH ) 8.4 Hz, J HH ) 7.6 Hz), 7.20 (dd, C6H4, 1H, J HH ) 8.2
3
3
Hz, J HH ) 7.6 Hz), 6.93 (d, C6H4, J HH ) 8.2 Hz, 1H), 1.61 (s,
tBu, 9H), 1.43 (s, Bu, 18H). 13C (1H) NMR (50 MHz, CDCl3;
t

2710 Organometallics, Vol. 20, No. 13, 2001
Vicente et al.
Ta ble 1. Deta ils of Da ta Collection a n d Str u ctu r e Refin em en t for th e Com p lexes 5a , 7a , 7b, 8b, 9a , a n d 12
5a
7a
7
8b
9a ‚C4H10
O
12
chem formula
cryst habit
cryst size/mm
λ/Å
cryst syst
space group
a/Å
C
17H13IN2O2Pd
C33H32IN3OPd
colorless column pale yellow lath orange prism
C35H34IN3O2Pd C27H24IN3O2Pd
C39H41F3N4O5PdS C96H88N8O4Pd4
yellow column
colorless tablet
yellow block
0.15 × 0.10 × 0.10
0.710 73
tetragonal
P4/n
0.25 × 0.05 × 0.04 0.7 × 0.2 × 0.15 0.7 × 0.2 × 0.06 0.26 × 0.09 × 0.07 0.45 × 0.4 × 0.12
0.710 73
triclinic
P1h
8.8284(3)
9.2319(4)
10.7891(3)
74.104(3)
89.026(3)
76.708(4)
822.04
0.710 73
triclinic
P1h
0.710 73
orthorhombic
Pbca
0.710 73
monoclinic
P21/n
0.710 73
triclinic
P1h
9.0188(14)
16.689(2)
21.851(3)
112.344(8)
90.559(10)
98.875(10)
2997.1
4
1.595
719.92
1432
Siemens P4
-100
50
14.8140(18)
20.550(2)
21.620(3)
90
10.0568(8)
13.3006(12)
18.6197(16)
90
8.5339(3)
14.9785(4)
17.2207(4)
112.118(3)
95.685(3)
101.822(3)
1957.95
2
19.5269(14)
19.5269(14)
12.2839(12)
90
90
90
b/Å
c/Å
R/deg
â/deg
90
90
103.876(3)
90
γ/deg
V/Å3
6581.4
8
2417.9
4
4683.8
2
Z
2
Dc/g cm-3
Mr
2.063
510.59
488
Siemens SMART
-100
52
1.538
1.802
1.427
1.307
761.95
3040
655.79
1288
841.22
864
1843.34
1872
F(000)
diffractometer
T/°C
Siemens P4
-100
50
Bruker SMART
-130
60
Siemens SMART
-100
56.6
Bruker SMART
-130
52.7
2θmax/deg
µ(Μo KR)/mm-1 3.0
1.68
0.79-0.93
13 576
1.54
2.07
0.59
0.81
transmissn
no. of rflns
measd
0.45-0.99
4775
0.68-0.89
5815
0.81-0.96
19 897
0.89-0.99
13 301
0.77-0.98
29 815
no. of unique
rflns
3181
10 263
5783
7041
9338
4796
Rint
0.043
0.058
0.016
0.025
0.053
723
0.17
0.039
0.068
421
0.041
0.038
0.084
310
0.017
0.034
0.084
483
0.101
0.038
0.111
261
R(F > 4σ(F))a
Rw(F2, all rflns)b 0.139
no. of params
209
no. of restraints 49
171
0.95
0.41
586
0.79
0.39
69
0.98
1.3
3
1.05
0.60
233
0.91
1.54
Sc
1.00
0.92
max ∆F/e Å-3
R(F) ) ∑||Fo| - |Fc||/∑|Fo|. Rw(F2) ) [∑{w(Fo - Fc2)2}/∑{w(Fo2)2}]0.5; w-1 ) σ2(Fo2) + (aP)2 + bP, where P ) [Fo + 2Fc2]/3 and a and
a
b
2
2
b are constants adjusted by the program. c S ) [∑{w(Fo2 - Fc2)2}/(n - p)]0.5, where n is the number of data and p the number of parameters.
Sch em e 1
Sch em e 2
are the first ortho-palladated complexes of phenol and
its derivatives.
nitrogen87,88 or phosphorus89 donor ligands, and we have
recently applied it to the synthesis of ortho-palladated
anilines.2,5 The trans geometry of 1a -c was confirmed
by the appearance of one singlet in their 31P NMR
spectra. Complexes 1b,c react with bpy in the presence
of Tl(OTf) (OTf ) OSO2CF3) to give the cationic species
[Pd(C6H4OR-2)(bpy)(PPh3)]OTf (R ) C(O)Me (3b), C(O)-
CHdCH2 (3c)) (Scheme 1). As far as we are aware, these
CO In ser tion s. We have tested the reactions of
complexes 1 and 2 with carbon monoxide, observing that
the ortho-palladated phenol derivatives 1a and 2a insert
CO to give the aroylpalladium complexes trans-[Pd-
{C(O)C6H4OH-2}I(PPh3)2] (4a ) and [Pd{C(O)C6H4OH-
2}I(bpy)] (5a ) (Scheme 2). With the palladated acetic
acid esters 1b and 2b a partial carbonylation takes
place; in the case of 1b the isolated solid is unreacted
1a with a very small amount of another compound
(87) Vanasselt, R.; Vrieze, K.; Elsevier, C. J . J . Organomet. Chem.
1994, 480, 27.
(88) Markies, B. A.; Canty, A. J .; Degraaf, W.; Boersma, J .; J anssen,
M. D.; Hogerheide, M. P.; Smeets, W. J . J .; Spek, A. L.; van Koten, G.
J . Organomet. Chem. 1994, 482, 191.
(89) Wallow, T. I.; Goodson, F. E.; Novak, B. M. Organometallics
1996, 15, 3708.

Ortho-Palladated Phenol Derivatives
Organometallics, Vol. 20, No. 13, 2001 2711
1
Sch em e 3
(detected by H NMR) that could be the expected CO-
inserted species. 2b is partially carbonylated to give a
40:60 mixture of 2b and a compound which is probably
the compound [Pd{C(O)C6H4O[C(O)Me]-2}I(bpy)]. An
increase in either the reaction time or the temperature
did not change the 40:60 ratio of the mixture. The
palladated acrylic acid ester does not react at all with
CO under our conditions. We conclude that the reactiv-
ity of our compounds toward CO insertion is dependent
mainly on the nature of the ortho OR group, the reac-
tivity order being OH . OC(O)Me > OC(O)CHdCH2.
Complex 4a reacts with bpy and Tl(OTf) to give the
cationic aroyl complex [Pd{C(O)C6H4OH-2}(bpy)(PPh3)]-
OTf (6a ). These carbonylated compounds are character-
1
ized by the presence in their H NMR spectra of a signal
at ca. 8.6 ppm, corresponding to the aryl proton ortho
to the carbonyl group (see Experimental Section).
The only previously isolated aroylpalladium com-
plexes derived from carbonylation of arylpalladium
derivatives are of two kinds: trans-[Pd{C(O)C6H4R-4}-
XL2] (R ) C6H4PdI(PEt3)2, PdI(PEt3)2, X ) I, L ) PEt3;57
R ) H, X ) Br, L ) PPh3,51,52 X ) I, L ) PCy3, PMe2-
Ph53 PMePh254) and [Pd{C(O)C6H4R-4}(µ-X)L]2 (R ) H,
Me, L ) PPh3, X ) I;56 R ) H, L ) PBu3, X ) Cl55). We
have recently reported the complexes [Pd{C(O)C6H4R-
2}IL2] (R ) NH2, NdCHPh, L2 ) 2 PR3, bpy) and some
of their derivatives [Pd{C(O)C6H4NH2-2}L2]OTf.2 There-
fore, these complexes and those reported here are the
products of the first carbonylation reactions of function-
alized aryl palladium complexes and also the first not
containing phosphines as ligands.
R ea ct ion s w it h Ison it r iles. The addition of 2-
ROC6H4I (R ) H, C(O)Me) to a mixture of “Pd(dba)2”
and the isonitrile R′NC (R′ ) C6H3Me2-2,6 (Xy), tBu) in
toluene yields the isonitrile-inserted complexes trans-
[Pd{C(dNR′)C6H4OR-2}I(CNR′)2] (R ) H, R′ ) Xy (7a ),
tBu (7a *); R ) C(O)Me, R′ ) Xy (7b), tBu (7b*)) (Scheme
3). Complex 7b* was obtained impurified by dba but was
prepared using a different method (see below). Instead
of the required 3:1:1 molar ratio of reagents R′NC:2-
ROC6H4I:Pd, an excess of the arene and, in the case of
7a and 7a *, substoichiometric amounts of the isonitrile
were used (3.2:1:2 (7a ), 1.2:1:2 (7a *), 1.2:1:3 (7b)). When
these reactions were carried out with the stoichiometric
ratio R′NC:Pd, it was not possible to isolate complexes
7a and 7a *. The homologous complex using tBuNC and
2-CH2dCHC(O)OC6H4I seems to be in the mixture
obtained in the corresponding reaction, as indicated by
the NMR spectra, but it could not be isolated as an
analytically pure compound, nor could the analogous
complex with XyNC be obtained.
CH2CO2Me, X ) Cl) but not insertion products.91 Otsuka
showed that similar complexes with R ) CH2Ph, X )
Br, I could be isolated by reacting “Pd(CNtBu)2” with
XR but with X ) Cl the complex [Pd{C(dNtBu)CH2Ph}-
Cl(CNtBu)]2 was obtained.72 Similarly, the reaction of
“Pd(CNtBu)2” with trans-BrCHdCHCO2Me gave [Pd-
{C(dNtBu)CHdCHCO2Me}Br(CNtBu)]2. In our case,
such dimeric complexes were not obtained. We assume
that the resulting [Pd(R)I(CNR′)2] (or the corresponding
dimeric complex) quickly decomposes to give 7a or 7a *
and some polymeric complex (eq 3) that could be
responsible of the formation of the mixture observed
when using the 3:1 stoichiometric amount of the isoni-
trile. When R ) C(O)Me, X ) I, and R′ ) Xy, the
intermediate [Pd(R)I(CNR′)2] would be stable and could
react with more isonitrile to give 7b.
The reaction between isonitriles and Pd(0) complexes
have been shown to give “Pd(CNtBu)2” (eq 1).90
Insertion reactions of isonitriles with organopalla-
dium complexes have been widely studied, but the
above-mentioned work of Otsuka72 is the only precedent
of the method we describe here. However, as already
mentioned, the results are different, and the com-
plexes involved are alkyl instead of aryl palladium
complexes. Iminoacyl and -aroyl palladium complexes
have been obtained (i) by reacting isonitriles with
“Pd(dba)2” + 2R′NC f “Pd(CNR′)2”
“Pd(CNR′)2” + RX f [Pd(R)X(CNR′)2]
(1)
(2)
[Pd(R)X(CNR′)2] f 2/3[Pd{C(dNR′)R}X(CNR′)2] +
1/3“Pd(R)X” (3)
(90) Otsuka, S.; Nakamura, A.; Tatsuno, Y. J . Am. Chem. Soc. 1969,
91, 6994.
(91) Otsuka, S.; Nakamura, A.; Yoshida, T.; Naruto, M.; Ataka, K.
J . Am. Chem. Soc. 1973, 95, 3180.
Reactions between acyl, aroyl, and alkyl chlorides and
“Pd(CNtBu)2” give the complexes [Pd(R)X(CNtBu)2] (eq
2; R ) MeC(O), PhC(O), (CH2)2CO2Et, CH(Ph)CO2Et,

2712 Organometallics, Vol. 20, No. 13, 2001
Vicente et al.
alkyl,45,64,67,70,72,78,83,84,92-94 aryl,4,45,57,76,78,85,93,95-97 alky-
nyl,67,71,74,98 or other organopalladium complexes68,72,73,99
(ii) via a transmetalation reaction involving an organo-
sodium68 or organomercury compound100 and a pal-
ladium isonitrile complex, or (iii) by thermal rearrange-
ment of an organo(isonitrile)palladium complex.101-103
Complex 7a or 7b* can also be prepared by ligand
displacement from 2a or 2b and XyNC or tBuNC,
respectively, in an 1:3 molar ratio. The bpy ligand is
substituted by two isonitriles, and a third isonitrile
inserts into the Pd-C bond (Scheme 3). This method
complements the previous one, since complex 7b* can
now be obtained as a pure compound. However, when
2b is reacted with XyNC in a 1:3 molar ratio, the
isonitrile inserts into the C-Pd bond but does not
replace bpy, giving complex 8b (see below).
Sch em e 4
Most of the many reported iminoaroyl palladium
complexes obtained by insertion of an isonitrile into a
C-Pd bond have some additional phosphorus, nitrogen,
oxygen, or sulfur donor ligand(s). The only exceptions
are the complexes [Pd{µ-C(dNR′)R}X]2 (R ) C6F5, R′
) Me, p-tolyl, X ) halide),104 [Pd{µ-C(dNR′)R}XL] (R
) C6F5, R′ ) Me, X ) Cl, L ) MeNC;101 R ) R′ ) Ph,
p-MeOC6H4, X ) Cl, L ) RNC),100 and [Pd{C(dNR′)R}-
Cl(CNR′′)] (R ) 2-C6H4CH2NMe2, R′ ) p-MeC6H4,
R′′ ) tBu)96 and the doubly inserted complex [Pd-
{{C(dNR′)}2R}Cl(CNR′)2] (R ) 2-C6H4N2Ph, R′ )
C6H11).97 The complexes 7 thus represent a new type of
iminoaroyl palladium complex.
iodide by bpy to form the cationic complex [Pd{C-
(dNXy)C6H4OH-2}(CNXy)(bpy)]OTf (9). It is notewor-
thy that bpy replaces XyNC, whereas this ligand
replaces bpy in complex 2a to give 7a . We are not aware
of the existence of any complex related to 9.
When complexes 2a ,b react with R′NC in a 1:1 ratio,
the bpy ligand is not displaced by the isonitrile, which
inserts into the corresponding aryl-palladium bond to
give the iminoaroyl palladium derivatives [Pd{C(dNR′)-
We have attempted the coinsertion of CO and R′NC,
and thus, we have (i) reacted the CO-inserted complex
5a with R′NC in a 1:2 ratio, whereupon only displace-
ment of the bpy ligand occurs, giving trans-[Pd{C(O)-
t
C6H4OR-2}I(bpy)] (R ) H, R′ ) Xy (8a ), Bu (8a *); R )
C(O)Me, R′ ) Xy (8b)). As mentioned above, complex
8b is obtained even if an excess of the isonitrile is
used. The only known complexes related to 8 are [Pd-
t
C6H4OH-2}I(CNR′)2] (R′ ) Xy (10a ), Bu (10a *)), and
(ii) reacted these complexes with further R′NC in the
presence of Tl(OTf), whereby only the cationic complexes
t
{C(dNR′)R}X(L2)], where R ) Me, R′ ) Xy, Bu, CH2-
t
[Pd{C(O)C6H4OH-2}(CNR′)3]OTf (R′ ) Xy (11a ), Bu
tosyl, X ) Cl, and L2 ) bpy, phen;64 they thus represent
a new type of iminoaroyl palladium complexes.
(11a *)) were obtained (Scheme 3).
In an attempt to prepare a trinuclear complex such
as A (Scheme 4) by reaction of 7a with Pd(OAc)2 in a
2:1 molar ratio, exploiting the acidity of the phenolic
proton, we obtained instead an easily separable mixture
of [PdI2(CNXy)2] and the tetrameric [Pd{κ2(C,O)-µ2(O)-
C(dNXy)C6H4O-2}(CNXy)]4 (12). Therefore, although
the expected acid-base reaction took place, the result-
ing “naked” Pd(II) removed the iodo and one isonitrile
ligand from each molecule of 7a , giving [PdI2(CNXy)2].
The structure of 12 has been confirmed by X-ray
diffraction, as shown below.
Sp ectr oscop ic P r op er ties. The 1H NMR signal
corresponding to the OH group in complex 1a or 2a
appears as a singlet at 4.99 or 5.82 ppm, respectively.
This signal is shifted to much higher frequency in the
CO-inserted complexes (4a , 9.72 ppm; 6a , 10.08 ppm;
5a , 10.25 ppm) or still higher in the isonitrile-inserted
complexes (7a , 13.66 ppm; 7a *, 15.89 ppm; 8a *, 13.90
ppm; 9a , 13.36 ppm). These changes may be associated
with to the deshielding caused by an intramolecular
hydrogen bond between the OH group and the carbonyl
oxygen or the imine nitrogen, which would result in the
formation of a six-membered ring (Chart 1). This has
been confirmed by X-ray diffraction studies carried out
for 5a , 7a , and 9a (see below). Complexes 10a , 10a *,
In an attempt to prepare the doubly inserted complex
[Pd{{C(dNXy)}2C6H4OH-2}(CNXy)(bpy)]+, we reacted
7a with bpy in the presence of Tl(OTf), which however
led instead to the substitution of one isonitrile and the
(92) Campora, J .; Hudson, S. A.; Massiot, P.; Maya, C. M.; Palma,
P.; Carmona, E.; Martinez Cruz, L. A.; Vegas, A. Organometallics 1999,
18, 5225.
(93) Yamamoto, Y.; Tanase, T.; Yanai, T.; Asano, T.; Kobayashi, K.
J . Organomet. Chem. 1993, 456, 287.
(94) Otsuka, S.; Nakamura, A.; Yoshida, T. J . Am. Chem. Soc. 1969,
91, 7196.
(95) Zografidis, A.; Polborn, K.; Beck, W.; Markies, B. A.; van Koten,
G. Z. Naturforsch., B 1994, 49, 1494.
(96) Yamamoto, Y.; Yamazaki, H. Inorg. Chim. Acta 1980, 41, 229.
(97) van Baar, J . F.; Klerks, J . M.; Overbosch, P.; Stufkens, D. J .;
Vrieze, K. J . Organomet. Chem. 1976, 112, 95.
(98) Takei, F.; Yanai, K.; Onitsuka, K.; Takahashi, S. Chem. Eur.
J . 2000, 6, 983.
(99) Vicente, J .; Saura-Llamas, I.; Turp´ın, J .; Ram´ırez de Arellano,
M. C.; J ones, P. G. Organometallics 1999, 18, 2683.
(100) Crociani, B.; Nicolini, M.; Richards, R. L. J . Organomet. Chem.
1976, 104, 259.
(101) Uso´n, R.; Fornie´s, J .; Espinet, P.; Lalinde, E.; J ones, P. G.;
Sheldrick, G. M. J . Chem. Soc., Dalton Trans. 1982, 2389.
(102) Uso´n, R.; Fornie´s, J .; Espinet, P.; Lalinde, E. J . Organomet.
Chem. 1983, 254, 371.
(103) Uso´n, R.; Fornie´s, J .; Espinet, P.; Pueyo, L.; Lalinde, E. J .
Organomet. Chem. 1986, 299, 251.
(104) Uso´n, R.; Fornie´s, J .; Espinet, P.; Lalinde, E.; Garc´ıa, A.; J ones,
P. G.; Meyer-Ba¨se, K.; Sheldrick, G. M. J . Chem. Soc., Dalton Trans.
1986, 259.

Ortho-Palladated Phenol Derivatives
Organometallics, Vol. 20, No. 13, 2001 2713
F igu r e 2. Thermal ellipsoid plot of one of the two
independent molecules of the complex 7a (30% probability
levels) with the labeling scheme. Selected bond lengths (Å)
and angles (deg): Pd-C(3), 1.979(3); Pd-C(4), 1.982(3);
Pd-C(1), 2.044(3); Pd-I, 2.7009(5); O-C(12), 1.350(4);
N(2)-C(1), 1.282(4); N(3)-C(3), 1.147(4); N(4)-C(4), 1.146-
(4); C(3)-Pd-C(1), 91.32(11); C(4)-Pd-C(1), 87.61(11);
C(3)-Pd-I, 91.22(8); C(4)-Pd-I, 89.74(8); C(1)-N(2)-
C(21), 123.8(2); C(3)-N(3)-C(31), 169.5(3); C(4)-N(4)-
C(41), 179.0(3); N(3)-C(3)-Pd, 174.6(3); N(4)-C(4)-Pd,
177.5(3).
F igu r e 1. Thermal ellipsoid plot of complex 5a (50%
probability levels) with the labeling scheme. Selected bond
lengths (Å) and angles (deg): Pd-C(1), 1.998(10);
Pd-N(22), 2.102(8); Pd-N(12), 2.159(7); Pd-I, 2.5883(9);
C(1)-O(1), 1.202(11); C(1)-Pd-N(22), 95.4(3); N(22)-Pd-
N(12), 78.4(3); C(1)-Pd-I, 87.7(3); N(12)-Pd-I, 98.4(2).
Ch a r t 1
11a , and 11a * show a singlet at 10.79, 10.78, 10.31, and
10.42 ppm, respectively, shifts very similar to those of
4a , 6a , and 5a . In consequence, we propose a hydrogen
bond between the OH and the carbonyl oxygen in these
complexes. In o-hydroxyacetophenone the OH proton
resonance appears at 12.25 ppm. We have reported
similar intramolecular hydrogen bonding in trans-[Pd-
{C(O)C6H4NH2-2}I(PMe3)2] between the aroyl oxygen
and one of the ortho NH2 protons.2
The band assignable to ν(OH) in complexes with R )
H is clearly observed only in the case of 2a . In all other
cases it is weak and broad and has not been assigned.
Those complexes with R ) C(O)Me show one band from
ν(CO) in the narrow range 1768-1746 cm-1, 17-39
cm-1 lower than in C6H4{OC(O)Me}-I-2 (1785 cm-1).
This is probably because of the lower electron-with-
drawing effect on the aryl ligand of the ortho groups in
the complexes (“PdIL2” in 1b, 2b, 3b; “{C(dNR′)}PdIL2”
in 7b, 7b*, 8b) compared to that of the iodine substitu-
ent in the starting compound. Similarly, complexes 1c
and 3c show ν(CO) bands at lower frequencies (1726
and 1734 cm-1, respectively) than the corresponding one
in the iodoarene C6H4OC(O)CHdCH2-I-2 (1745 cm-1).
The band corresponding to ν(CtN) appears in the region
2224-2190 or 2192-2158 cm-1 for complexes contain-
ing tBuNC or XyNC, respectively. The band correspond-
ing to ν(CdN) appears in a wide range (1642-1536
cm-1). The factor with the greatest effect on the fre-
quency of this band is the nature of the group R,
F igu r e 3. Thermal ellipsoid plot of the complex 7b (30%
probability levels) with the labeling scheme. Selected bond
lengths (Å) and angles (deg): Pd-C(3), 1.954(5); Pd-C(4),
1.977(5); Pd-C(1), 2.058(5); Pd-I, 2.7121(6); O(1)-C(17),
1.365(7); O(1)-C(12), 1.407(6); O(2)-C(17), 1.193(6);
N(2)-C(1), 1.259(6); N(3)-C(3), 1.157(5); N(4)-C(4), 1.139-
(5); C(3)-Pd-C(1), 90.0(2); C(4)-Pd-C(1), 87.7(2);
C(3)-Pd-I, 91.60(15); C(4)-Pd-I, 90.62(15); C(17)-O(1)-
C(12), 115.4(4); C(1)-N(2)-C(21), 124.0(5); C(3)-N(3)-
C(31), 172.8(6); C(4)-N(4)-C(41), 174.7(5); N(3)-C(3)-Pd,
178.0(5); N(4)-C(4)-Pd, 177.7(5).
ascribable to R (16-62 cm-1), giving the following order
of ν(CdN): 7b* > 7b > 7a * > 7a ; 8b > 8a * > 8a .
X-r a y Cr ysta l Str u ctu r es of Com p lexes 5a , 7a , 7b,
8b, 9a , a n d 12. The structures of these complexes show
the usual square-planar arrangement about the pal-
ladium atom (5a (Figure 1), 7a (Figure 2), 7b (Figure
3), 8b (Figure 4), 9a (Figure 5) and 12 (Figure 6)). The
crystal structure of 7a involves two independent but
essentially similar molecules (rms deviation of all non-H
atoms 0.11 Å). In those complexes with bpy, the
geometry is distorted because of the small bite angle of
this ligand. The different Pd-I and Pd-N bond dis-
tances can be used to order the trans influence of some
ligands. Thus, the Pd-I bond distances (in Å) are
because, other groups being equal, ν(CdN)C(O)Me
-
ν(CdN)H ) 30-78 cm-1. Certainly, the intramolecular
O-H‚‚‚N hydrogen bonding must be responsible for this
effect (ν(CdN)C(O)Me ) 1636-1586 cm-1; ν(CdN)H
)
1572-1536 cm-1). As expected,64 ν(CdN) Bu > ν(CdN)Xy
t
for the same R but the difference is lower than that

2714 Organometallics, Vol. 20, No. 13, 2001
Vicente et al.
F igu r e 4. Thermal ellipsoid plot of the complex 8b (50%
probability levels) with the labeling scheme. Selected bond
lengths (Å) and angles (deg): Pd-C(1), 1.994(4); Pd-N(1),
2.114(3); Pd-N(2), 2.153(3); Pd-I, 2.5904(4); N(3)-C(1),
1.267(5); C(42)-O(1), 1.424(5); C(47)-O(2), 1.190(6);
C(47)-O(1), 1.326(6); C(1)-Pd-N(1), 95.85(14); C(1)-Pd-
N(2), 173.12(14); N(1)-Pd-N(2), 77.28(12); C(1)-Pd-I,
88.89(10); N(1)-Pd-I, 175.07(9); N(2)-Pd-I, 97.98(9);
C(1)-N(3)-C(31), 126.6(3).
F igu r e 6. Thermal ellipsoid plot of complex 12 (30%
probability levels) with the labeling scheme. Hydrogen
atoms are omitted for clarity. Selected bond lengths (Å) and
angles (deg): Pd-C(10), 1.926(5); Pd-C(20), 2.004(4);
Pd-O(1), 2.052(3); Pd-O(1)#1, 2.195(3); O(1)-Pd#2, 2.195-
(3); C(10)-N(1), 1.155(6); C(10)-Pd-C(20), 96.0(2);
C(20)-Pd-O(1), 84.99(16); C(10)-Pd-O(1)#1, 93.68(16);
O(1)-Pd-O(1)#1, 85.09(13); C(32)-O(1)-Pd, 111.1(3);
C(32)-O(1)-Pd#2, 123.1(3); Pd-O(1)-Pd#2, 122.50(14);
N(1)-C(10)-Pd, 170.8(4); C(10)-N(1)-C(11), 173.3(5);
C(20)-N(2), 1.265(6).
C6H4OC(O)Me-2, 2.153(3) (8b). If the values for the
neutral complexes are compared, the order of trans
influence is I < C(dNXy)C6H4OC(O)Me-2 ≈ C(dO)C6H4-
OH-2. In the cationic complex 9b , the order of trans
influence is XyNC < C(dNXy)C6H4OH-2. When the
Pd-C(dNXy)C6H4OC(O)Me-2 bond distances in 7b
(2.058(5) Å) and in 8b (1.994(4) Å) are compared, the
order of trans influence is bpy < I. Therefore, from the
above series we propose the following scale of trans
influence: bpy < I < C(dNXy)C6H4OC(O)Me-2 ≈
C(dO)C6H4OH-2 < C(dNXy)C6H4OH-2. The aroyl and
iminoaroyl C-Pd bond distances only depend on the
nature of the trans ligand because the related pairs of
complexes 5a (1.998(10) Å)/8b (1.994(4) Å), with bpy
trans, and 7a (2.044(3) Å)/7b (2.058(5) Å), with iodo
trans, have similar C-Pd bond distances.
An intramolecular hydrogen bond is established be-
tween the OH group at O(2) and the carbonyl oxygen
O(1) in 5a (O-H, 0.84 Å; OH‚‚‚O, 1.83 Å; O‚‚‚O, 2.559-
(9) Å; O-H‚‚‚O, 144.2(4)°), from the OH group to the
imine N(2) nitrogen in both molecules of 7a (O-H, 0.76-
(3) Å; H‚‚‚N, 1.90(3) Å; 1.89(3) Å; O‚‚‚N, 2.584(3), 2.579-
(3) Å; O-H‚‚‚N, 151(3), 150(4)°) and from O(1)-H to
N(1) in 9a (O-H, 0.84 Å; H‚‚‚N, 1.83 Å; O‚‚‚N, 2.571(3)
Å; O-H‚‚‚N, 144.2(4)°) giving a six-membered ring
(Chart 1). This type of interaction may reasonably be
postulated as the cause of the high frequency of the
1H NMR resonance observed for the OH proton and
the low frequency of the ν(CdN) band in these and
related complexes (see above). The following addition-
al nonclassical hydrogen bonds are observed: 5a ,
F igu r e 5. Thermal ellipsoid plot of the cation of complex
9a (30% probability levels) with the labeling scheme.
Selected bond lengths (Å) and angles (deg): Pd-C(40),
1.926(2); Pd-C(7), 2.017(2); Pd-N(22), 2.0739(18); Pd-
N(32), 2.1173(19); O(1)-C(2), 1.348(3); N(1)-C(7), 1.283-
(3); C(40)-Pd-C(7), 85.68(9); C(7)-Pd-N(22), 96.27(8);
C(40)-Pd-N(32), 99.40(9); N(22)-Pd-N(32), 78.98(7); C(7)-
N(1)-C(11), 124.1(2); C(40)-N(2)-C(41), 172.6(2); N(2)-
C(40)-Pd, 173.8(2).
2.5883(9) (5a), 2.7009(5) (7a), 2.7121(6) (7b), and 2.5904-
(4) (8b). Therefore, the order of trans influence is bpy
, C(dNXy)C6H4OC(O)Me-2 < C(dNXy)C6H4OH-2. The
Pd-N bond distances (in Å) in bpy complexes are as
follows: trans to I, 2.102(8) (5a ) and 2.114(5) (8b); trans
to C(dO)C6H4OH-2, 2.159(7) (5a ); trans to C(dNXy)-

Ortho-Palladated Phenol Derivatives
Organometallics, Vol. 20, No. 13, 2001 2715
C(23)-H(23)‚‚‚O(2) with H‚‚‚O ) 2.46 Å and C H‚‚‚O )
139°; 9a , seven H bonds to triflate and ether oxygens,
of which the shortest is C(34)-H(34)‚‚‚O(2) with H‚‚‚O
) 2.45 Å, C-H‚‚‚O ) 167°.
and [Pd{κ2(P,O)-µ(O)-Ph2P(C6H3(OH)-3-O-6}Br]4106 (C).
These complexes, obtained by routes completely differ-
ent from that of 12, have in common with it the presence
of a chelating (E-X-Y-O)n- ligand (12, E ) C, n ) 2;
B, E ) N, n ) 1; C, E ) P, n ) 1). Complex B has been
found to catalyze the allylic oxidation of cyclohexene.105
The X-ray diffraction study of 12 (Figure 6) reveals a
tetrameric structure with crystallographic 4-fold sym-
metry, consisting of a highly distorted cubic array of
alternating palladium and oxygen atoms; the nonbonded
axial Pd‚‚‚O contacts along the open sides of the cube
are typically long at 3.097(3) Å. A schematic representa-
tion of the structure is shown in Scheme 4. Each
palladium atom displays a distorted-square-planar ge-
ometry formed with a chelating C,O iminoacylphenolato
ligand, XyNC, and the oxygen atom of an adjacent
fragment. The oxygen atoms are unsymmetrically bonded
to two palladium atoms (Pd-O(1), 2.052(3) Å; Pd-O(1)#,
2.195(3) Å). The shorter bond distances correspond to
those in the chelating ligand. A search of the Cambridge
Crystallographic Database revealed only two precedents
for this type of structure in palladium complexes, [Pd-
{κ3(C,N,O)-µ2(O)-C6H4(CHMeNdCHC6H4O-2)-2}]4105 (B)
Ack n ow led gm en t. We thank Direccio´n General de
Investigacio´n Cient´ıfica y Te´cnica (Grant No. PB97-
1047), INTAS (Grant No. 97-166), and the Fonds der
Chemischen Industrie for financial support. W.F. is
grateful to the DGESIC of Spain for a grant.
Su p p or tin g In for m a tion Ava ila ble: X-ray crystallo-
graphic files, in CIF format, for 5a , 7a , 7b, 8b, 9a , and 12.
This material is available free of charge via the Internet at
http://pubs.acs.org.
OM010074Z
(105) Yang, H.; Khan, M. A.; Nicholas, K. M. J . Chem. Soc., Chem.
Commun. 1992, 210.
(106) Sembiring, S. B.; Colbran, S. B.; Craig, D. C.; Scudder, M. L.
J . Chem. Soc., Dalton Trans. 1995, 3731.